JP2012233429A - Jet engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel consumption while reducing noise, in a jet engine having a noise reduction structure around a jet flow nozzle.SOLUTION: The jet engine includes a plasma actuator 70 disposed at a position where the noise reduction structure 1 is installed, and for generating a volume force that promotes change in a flow field of a jet flow caused by the noise reduction structure 1.

Description

  The present invention relates to a jet engine.

Conventionally, as a noise countermeasure for a jet engine mounted on an aircraft, as shown in Patent Document 1 and Patent Document 2, a jet engine having a noise reduction structure around an opening of a jet jet nozzle is disclosed. Proposed.
According to the jet engine having such a noise reduction structure, for example, mixing of the jet jet and the external flow is promoted by the noise reduction structure, thereby reducing noise.

US Pat. No. 7,246,481 JP 2003-172205 A

However, since the noise reduction structure changes the jet jet flow field, the noise reduction structure needs to be arranged in the jet jet flow.
For this reason, the engine throat surface and the exit effective area of the nozzle having the noise reduction structure are significantly different from those of the nozzle not having the noise reduction structure, and the flow coefficient is reduced. Therefore, in order to cover the reduction of the flow coefficient, it is necessary to increase the opening diameter of the nozzle, which increases the weight of the jet engine.
In addition, the more complicated the shape of the noise reduction structure is, the more the nozzle performance deteriorates at non-design points and the thrust is reduced, so when trying to obtain the same level of thrust as a nozzle without a noise reduction structure Therefore, it is necessary to increase the engine output as compared with the conventional case.
In addition, noise can be reduced especially when climbing close to the ground surface (from stopping to accelerating to the cruising state), but the conventional noise reduction structure is capable of jet jets even during cruising. Placed in the flow. For this reason, the thrust at the time of the cruising in which the reduction of noise is not required will also fall unintentionally.
That is, by providing the noise reduction structure, the noise can be reduced, but the fuel required due to a decrease in thrust or the like increases, leading to deterioration in fuel consumption.

In addition, some low noise structures have been proposed in which noise is reduced by bending a mixed layer of a jet jet and an external flow as viewed from the injection direction.
Even in such a noise reduction structure, the noise reduction structure is disposed in the jet flow in order to bend the mixing layer, and the same problem occurs.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to improve fuel efficiency while reducing noise in a jet engine having a noise reduction structure around the opening of a jet jet nozzle.

  The present invention adopts the following configuration as means for solving the above-described problems.

  A first aspect of the present invention is a jet engine having a noise reduction structure in which a jet jet nozzle that jets a jet jet to the outside reduces noise by changing a flow field of the jet jet around an injection opening, the noise reduction A configuration is adopted in which a plasma actuator is provided that generates a body force that is disposed at the installation position of the structure and promotes a change in the flow field of the jet jet generated by the noise reduction structure.

  According to a second aspect of the present invention, in the first aspect of the present invention, the jet jet nozzle is a notch nozzle including a plurality of protrusions protruding toward the center of the injection opening as the noise reduction structure.

  According to a third aspect of the present invention, in the first aspect, the jet jet nozzle is a chevron nozzle including a plurality of triangular notches formed at an edge forming the injection opening as the noise reduction structure. Is adopted.

  According to a fourth invention, in any one of the first to third inventions, the plasma actuator is installed on an outer wall surface of the jet jet nozzle.

  According to a fifth invention, in any one of the first to third inventions, the plasma actuator is installed on an inner wall surface of the jet jet nozzle.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the plasma actuator is operated with surplus power generated in the jet engine.

  According to a seventh invention, in any one of the first to sixth inventions, the plasma actuator is operated only until an aircraft on which the jet engine is mounted is accelerated from a stop state to a cruise state. Is adopted.

According to the present invention, the volume force generated by the plasma actuator facilitates the change in the jet jet flow field caused by the noise reduction structure.
For this reason, for example, even if the noise reduction structure is small and the change in the jet jet flow field is not sufficient with the noise reduction structure alone, the change in the jet jet flow field is facilitated by the volume force generated by the plasma actuator. By doing so, a large noise reduction effect can be obtained.
In other words, according to the present invention, by providing the plasma actuator, the size of the noise reduction structure can be reduced, and the area blocking the jet jet can be reduced. As a result, the above-described increase in the weight of the jet engine, increase in engine output, and reduction in thrust during cruising can be suppressed.
Therefore, according to the present invention, in a jet engine having a noise reduction structure around the opening of the jet jet nozzle, it is possible to improve fuel efficiency while reducing noise.

It is sectional drawing which shows typically schematic structure of the jet engine in 1st Embodiment of this invention. It is the front view which looked at the jet jet nozzle with which the jet engine in 1st Embodiment of this invention is provided from the side by which a jet jet is injected. It is an enlarged view which shows typically the field including the projection part with which the jet engine in a 1st embodiment of the present invention is provided. It is a schematic diagram of the plasma actuator with which the jet engine in 1st Embodiment of this invention is provided. It is a graph which shows the pressure around the projection part with which the jet engine in 1st Embodiment of this invention is provided. It is a schematic diagram which shows the example of arrangement | positioning of the plasma actuator with which the jet engine in 1st Embodiment of this invention is provided. It is a schematic diagram which shows the example of arrangement | positioning of the plasma actuator with which the jet engine in 1st Embodiment of this invention is provided. It is a schematic diagram which shows the example of arrangement | positioning of the plasma actuator with which the jet engine in 1st Embodiment of this invention is provided. It is sectional drawing which shows typically schematic structure of the jet engine in 2nd Embodiment of this invention. It is a schematic diagram which shows the example of arrangement | positioning of the plasma actuator with which the jet engine in 2nd Embodiment of this invention is provided. It is a schematic diagram which shows the example of arrangement | positioning of the plasma actuator with which the jet engine in 2nd Embodiment of this invention is provided.

  Hereinafter, an embodiment of a jet engine according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

(First embodiment)
FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a jet engine 10 of the present embodiment.
As shown in this figure, the jet engine 10 of the present embodiment includes a fan 20, a compressor 30, a combustor 40, a turbine 50, a jet jet nozzle 60, and a plasma actuator 70 (see FIG. 3). I have.
In addition, these fans 20, the compressor 30, the combustor 40, the turbine 50, and the jet jet nozzle 60 are arranged in the flow direction of air.

The fan 20 is for taking air into the inside of the jet engine 10 from the outside, and is driven by the transmission of power from the turbine 50 arranged at the subsequent stage.
The compressor 30 compresses the air taken in by the fan 20, and is driven by power transmitted from the turbine 50 arranged at the subsequent stage, similarly to the fan 20.
The combustor 40 generates high-temperature and high-pressure gas by burning the air and fuel compressed by the compressor 30.
The turbine 50 converts part of the energy of the high-temperature and high-pressure gas supplied from the combustor 40 into rotational power, and is physically connected to the fan 20 and the compressor 30.
The jet jet nozzle 60 injects high-temperature high-pressure gas supplied via the turbine 50 to the outside as a jet jet.

  FIG. 2 is a view of the jet jet nozzle 60 as viewed from the jet jet side, (a) is a view showing the entire jet jet nozzle 60, and (b) shows the region α in (a). It is an enlarged view. FIG. 3 is an enlarged perspective view including the jet jet nozzle 60.

As shown in these drawings, the jet jet nozzle 60 in the present embodiment is formed by a cylindrical partition wall having a nozzle outlet end 61, and jets a jet jet from the nozzle outlet end 61 (ejection opening).
The jet jet nozzle 60 in the present embodiment is a notch nozzle including a plurality of protrusions 1 provided around the nozzle outlet end 61 at equal intervals.

The protrusion 1 curves the mixed layer formed in the boundary region between the jet jet and the external air flow (flow of outside air flowing from the outside of the jet jet nozzle 60) when viewed from the jet jet side. This prevents an increase in the velocity gradient of the fluid in the mixed layer.
More specifically, when the protrusion 1 is not present, the shape of the mixed layer is circular as in the case of the nozzle outlet end 61, but the presence of the protrusion 1 causes the portion around the protrusion 1 to be in the circle. It curves so as to enter the inside of the circle from the circumference. When the mixed layer is curved by the protrusion 1, the mixed layer as viewed from the side from which the jet jet is ejected is apparently thick. As the mixed layer viewed from the jet jet side becomes thick in this manner, the velocity gradient in the mixed layer becomes gradual as compared with the case where the mixed layer does not bend without the protrusion 1 being present. Is prevented, and the shearing force in the mixed layer is reduced.
As a result, it is possible to reduce noise when the jet jet and the external flow are mixed. That is, in the present embodiment, the protrusion 1 corresponds to the noise reduction structure in the present invention.

  In the present embodiment, since the plurality of protrusions 1 are provided at equal intervals around the nozzle outlet end 61, the shape of the mixed layer is repeatedly curved in a wave shape along the circumference along the original nozzle outlet end 61. It becomes the shape.

  And in this embodiment, the protrusion part 1 is arrange | positioned only the number by which the mixed layer curves in the whole area | region of the perimeter, seeing from the jet jet side, and is specifically, equidistant. Has been placed.

Each protrusion 1 has a triangular pyramid shape protruding in the radial direction toward the center of the nozzle outlet end 61 viewed from the jet jet side.
Moreover, the jet jet nozzle 60 in this embodiment is provided with the groove part 2 which reaches | attains the nozzle exit end 61 continuously according to each projection part 1 on the outer side of a cylindrical partition, as shown in FIG.2 (b). Yes. That is, the groove 2 is provided on the outer side of the protrusion 1 (that is, the outer wall surface of the jet jet nozzle 60) in the radial direction of the nozzle outlet end 61.

3 is an enlarged view schematically showing a region including the protrusion 1, (a) is a view seen from the same direction as FIG. 1, and (b) is a view seen from the same direction as FIG. 2. It is. And in this embodiment, as shown in FIG. 3, the plasma actuator 70 is installed with respect to the groove part 2 formed in the back side of the projection part 1 of FIG.
That is, in the present embodiment, the plasma actuator 70 is provided for each protrusion 1 and is disposed on the outer wall surface of the jet jet nozzle 60.

  The plasma actuator 70 is disposed at the installation position of the protrusion 1 and promotes a change in the flow field of the jet jet generated by the protrusion 1. More specifically, in the present embodiment, in the plasma actuator 70, a part of the air on the outer wall surface side of the jet jet nozzle 60 is shown in FIG. 3 so that the curvature of the mixed layer formed by the protrusion 1 is promoted. The body force is generated so that the vortex B shown in FIG.

FIG. 4 is a schematic diagram of the plasma actuator 70. As shown in this figure, the plasma actuator 70 includes an insulating layer 71, a first electrode plate 72 disposed on the upper surface of the insulating layer 71, and a second electrode plate 73 disposed on the lower surface of the insulating layer 71. ing.
As shown in FIG. 4, the first electrode plate 72 and the second electrode plate 73 have a configuration in which they are displaced as viewed from the thickness direction of the insulating layer 71.
When power is supplied to the first electrode plate 72 and the second electrode plate 73 of the plasma actuator 70 connected to the AC power source 100, the thickness direction of the insulating layer 71 is on the side of the second electrode plate 72. As a result, plasma is generated in a region overlapping the second electrode plate 73. As a result, air in the region where the plasma is generated is ionized to generate body force, and an air flow indicated by an arrow is formed.

By using such a plasma actuator 70, a part of the air on the outer wall surface side of the jet jet nozzle 60 is caused to flow toward the jet jet side as indicated by an arrow A shown in FIG. The
Here, as shown in FIG. 5, the presence of the protrusion 1 causes a large pressure difference between the tip and the base of the protrusion 1. The stronger the vertical vortex generated by this pressure difference, the greater the effect of bending the mixing layer.
In this embodiment, the vortex B formed by the plasma actuator 70 can increase the pressure difference in the protrusion 1 to strengthen the vertical vortex, and the mixed layer formed by the protrusion 1 can be curved. Can help.

The plasma actuator 70 is electrically connected to an aircraft generator on which the jet engine 10 of the present embodiment is mounted, and operates when supplied with electric power generated by the generator.
Here, in consideration of the surrounding environment, it is particularly necessary to reduce the noise until the aircraft starts accelerating from the stopped state, the ascent is completed, and the cruise state is reached.
Therefore, in the jet engine 10 of this embodiment, it operates only until the aircraft on which the jet engine 10 is mounted accelerates from a stopped state to a cruise state.

Normally, in an aircraft, since the engine speed is high from the stop state to the cruising state, a large amount of electric power is generated and surplus electric power is generated.
And in the jet engine 10 of this embodiment, the said surplus electric power is supplied and operate | moves.

In general, in an aircraft, wiring for supplying electric power to an exciter installed in a combustion chamber is provided.
For this reason, the wiring connected to an exciter can be branched and connected to each plasma actuator 70, and electric power can be supplied to the plasma actuator 70 via the said wiring.

According to the jet engine 10 of the present embodiment, the change in the flow field of the jet jet generated by the protrusion 1 is promoted by the volume force generated by the plasma actuator 70.
For this reason, for example, even when the protrusion 1 is small and the change of the jet jet flow field is not sufficient with the protrusion 1 alone, the change of the jet jet flow field is caused by the volume force generated by the plasma actuator 70. By promoting, a large noise reduction effect can be obtained.
That is, according to the jet engine 10 of the present embodiment, by providing the plasma actuator 70, the size of the protrusion 1 can be reduced, and the area that blocks the jet jet can be reduced. As a result, an increase in the weight of the jet engine, an increase in engine output, and a reduction in thrust during cruising can be suppressed.
Therefore, according to the jet engine 10 of the present embodiment, it is possible to improve fuel efficiency while reducing noise.

Further, according to the jet engine 10 of the present embodiment, the plasma actuator 70 is installed on the outer wall surface of the jet jet nozzle 60.
For this reason, it can prevent that the plasma actuator 70 becomes a factor which narrows the opening area of the jet jet nozzle 60. FIG.
In addition, since the plasma actuator 70 is not exposed to the jet jet, the deterioration with time of the plasma actuator 70 can be delayed.

Further, according to the jet engine 10 of the present embodiment, the plasma actuator 70 is operated with surplus power generated in the jet engine 10.
For this reason, it is not necessary to separately provide a power source for operating the plasma actuator 70, and the plasma actuator 70 can be installed at low cost.

Further, according to the jet engine 10 of the present embodiment, the plasma actuator 70 is operated only until the aircraft on which the jet engine 10 is mounted accelerates from a stopped state to a cruise state.
For this reason, according to the jet engine 10 of the present embodiment, the noise is reduced until the aircraft that needs to reduce noise accelerates from the stopped state to the cruising state, and the noise needs to be reduced much. In the cruise state where the cruising is not performed, the degree of curvature of the mixed layer is relaxed and the thrust is improved.
Therefore, according to the jet engine 10 of the present embodiment, it is possible to efficiently improve fuel efficiency by reducing noise only when necessary.

In the jet engine 10 of the present embodiment, a configuration in which the plasma actuator 70 is disposed in the groove 2 is employed.
However, for example, as shown in FIGS. 6 and 7, a plasma actuator 70 may be installed on the outer wall surface of the protrusion 1 (the inner wall surface of the jet jet nozzle 60).
As described above, by installing the plasma actuator 70 on the inner wall surface of the jet jet nozzle 60, the change of the eddy current B formed by the plasma actuator 70 on the jet jet becomes large, and the mixed layer formed by the protrusion 1 The bending can be strongly promoted.
In order to efficiently form the vortex B, the flow direction formed by the plasma actuator 70 is preferably the direction facing the opposite side of the jet jet as shown by the arrow C in FIGS.

As shown in FIG. 6, by arranging the plasma actuator 70 on the tip side of the protrusion 1, a vortex B is formed closer to the center of the jet jet, and the bending of the mixed layer can be further strongly promoted. .
However, if the bending of the mixed layer is promoted too much, the thrust drop of the jet engine 10 becomes large. To avoid this, the plasma actuator 70 is disposed on the base side of the protrusion 1 as shown in FIG. May be.

In addition, as shown in FIG. 8, the plasma actuator 70 may be disposed on the side of the protrusion 1.
In this case, as shown in FIG. 8 (a), by installing the plasma actuator 70 on the inner wall surface of the jet jet nozzle 60, the change of the swirl jet jet formed by the plasma actuator 70 is increased, and the protrusions The bending of the mixed layer formed by 1 can be strongly promoted.
Further, as shown in FIG. 8B, by installing the plasma actuator 70 on the outer wall surface of the jet jet nozzle 60, it is possible to prevent the plasma actuator 70 from becoming a factor of narrowing the opening area of the jet jet nozzle 60. It is possible to delay deterioration of the plasma actuator 70 with time.
At this time, the electrode plate of the plasma actuator 70 is disposed so as to form a vortex toward the protrusion. The plasma actuator 70 itself may be directed in the direction of the vortex, or the electrode plates may be arranged diagonally in the plasma actuator 70.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the description of the present embodiment, the description of the same parts as those of the first embodiment is omitted or simplified.

FIG. 9 is a cross-sectional view schematically showing a schematic configuration of the jet engine 10A of the present embodiment.
As shown in this figure, the jet engine 10A of the present embodiment includes a jet jet nozzle 80 instead of the jet jet nozzle 60 provided in the jet engine 10 of the first embodiment.
The jet jet nozzle 80 of the present embodiment is a chevron nozzle that includes a plurality of triangular notches 3 at equal intervals on the edge forming the nozzle outlet end 81 (injection opening).

The notch 3 enhances the mixing effect of the jet jet and the external airflow in the boundary region, and aims to reduce noise by quickly mixing the jet jet and the external airflow.
That is, in this embodiment, the notch 3 corresponds to the noise reduction structure in the present invention.

In such a jet engine 10A of this embodiment, the notch 3 forms a vertical vortex, and this vertical vortex can enhance the mixing effect of the jet jet and the external airflow in the boundary region.
Also in the jet engine 10A of the present embodiment, as shown in FIGS. 10 and 11, by installing the plasma actuator 70 according to the notch 3, the longitudinal vortex is strengthened as in the first embodiment. This further enhances the mixing effect of the jet jet and the external airflow in the boundary region.

According to the jet engine 10A of this embodiment, the change in the flow field of the jet jet generated by the notch 3 is promoted by the volume force generated by the plasma actuator 70.
For this reason, for example, even when the notch 3 is small and the change in the jet jet flow field is not sufficient with the notch 3 alone, the change in the jet jet flow field is caused by the volume force generated by the plasma actuator 70. By promoting, a large noise reduction effect can be obtained.
That is, according to the jet engine 10A of the present embodiment, the size of the notch 3 can be reduced by providing the plasma actuator 70, and the mixing effect of the jet jet and the external airflow in the boundary region during cruising can be achieved. This can reduce the engine output and suppress the thrust drop during cruising.
Therefore, according to the jet engine 10A of the present embodiment, it is possible to improve fuel efficiency while reducing noise.

In this case, as shown in FIG. 10, by installing the plasma actuator 70 on the inner wall surface of the jet jet nozzle 80, the change of the eddy current jet formed by the plasma actuator 70 on the jet jet becomes large, and in the boundary region The mixing effect of the jet jet and external airflow can be further enhanced.
In addition, as shown in FIG. 11, by installing the plasma actuator 70 on the outer wall surface of the jet jet nozzle 80, it is possible to prevent the plasma actuator 70 from becoming a factor for narrowing the opening area of the jet jet nozzle 80. The deterioration with time of the plasma actuator 70 can be delayed.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, the jet engine of the present invention can also be applied to a turbofan engine that injects outside as a bypass flow without supplying a part of the taken-in air to the combustion chamber.
In this case, the plasma actuator and the noise reduction structure are installed in one or both of the core nozzle that injects the core flow discharged from the combustor and the bypass nozzle that injects the bypass flow.
In addition, when providing a plasma actuator and a noise reduction structure in a core nozzle, description similar to the said embodiment can be performed by catching the jet flow of the said embodiment as a core flow, and an external flow as a bypass flow.
Further, when a plasma actuator and a noise reduction structure are provided in the bypass nozzle, the jet nozzle flow of the above embodiment is regarded as a bypass flow, and the external flow is regarded as an air flow outside the bypass nozzle, thereby explaining the same as in the above embodiment. It can be performed.
That is, the jet jet in the present invention is a concept including a bypass flow.

Moreover, in the said embodiment, the structure which installs a plasma actuator according to all the noise reduction structures was demonstrated.
However, the present invention is not limited to this, and it is also possible to install a plasma actuator corresponding to some noise reduction structures.

  DESCRIPTION OF SYMBOLS 1 ... Projection part (noise reduction structure), 3 ... Notch (noise reduction structure) 10, 10A ... Jet engine, 60, 80 ... Jet jet nozzle, 61, 81 ... Nozzle exit end (injection opening) 70) Plasma actuator

Claims (5)

A jet engine having a noise reduction structure on a wall surface around a jet opening of a jet jet nozzle for jetting a jet jet to the outside,
A jet engine comprising a plasma actuator at an installation position of the noise reduction structure.   2. The jet engine according to claim 1, wherein the jet jet nozzle is a notch nozzle including a plurality of protrusions protruding toward the center of the injection opening as the noise reduction structure.   2. The jet engine according to claim 1, wherein the jet jet nozzle is a chevron nozzle having a plurality of triangular notches formed at an edge portion forming an injection opening as the noise reduction structure.   The jet engine according to claim 1, wherein the plasma actuator is operated by surplus power generated in the jet engine.   The jet engine according to any one of claims 1 to 4, wherein the plasma actuator is operated only until an aircraft on which the jet engine is mounted accelerates from a stopped state to a cruise state.

Images